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executor: make projection executor unparallel for insert/update/delete (#30290) #30387

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@ti-srebot ti-srebot commented Dec 3, 2021

cherry-pick #30290 to release-5.2
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/30387

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/tidb.git pr/30387:release-5.2-4fbbd5a77df2

What problem does this PR solve?

Issue Number: close #26832

Problem Summary:

The memdb is not thread-safe, and that's the root cause of issue 26832

What is changed and how it works?

In insert/update/delete statement, do not use the parallel projection, choose the unparallel one intead.

This can avoid the concurrent visit of the memdb in issue 26832.

Check List

Tests

  • Unit test
  • Integration test
  • Manual test (add detailed scripts or steps below)
  • No code

I try to add some unit test code like this and run it with -race flag, but can't reproduce.

+func (s *testSuite8) TestIssues26832DataRace(c *C) {
+       tk := testkit.NewTestKit(c, s.store)
+       tk.MustExec("use test")
+       tk.MustExec("drop table if exists t")
+       tk.MustExec("create table t (a int unique)")
+       tk.MustExec(`CREATE TABLE IF NOT EXISTS order_line (
+               ol_o_id INT NOT NULL,
+               ol_d_id INT NOT NULL,
+               ol_w_id INT NOT NULL,
+               ol_i_id INT NOT NULL,
+               ol_delivery_d INT,
+               PRIMARY KEY(ol_w_id, ol_d_id, ol_o_id)) partition by hash(ol_w_id) partitions 10`)
+       for i:=0; i<1000; i++ {
+               tk.MustExec("insert into order_line value (?, ?, ?, ?, ?)", i, i, i, i, i)
+       }
+
+       for i:=0; i<1000; i++ {
+               v := rand.Intn(1000)
+               tk.MustExec(`UPDATE order_line SET ol_delivery_d = ol_delivery_d + 1 WHERE (ol_w_id, ol_d_id, ol_o_id) IN (
+       (?,?,?),(?,?,?),(?,?,?),(?,?,?),(?,?,?),(?,?,?),(?,?,?),(?,?,?),(?,?,?),(?,?,?))`,
+                       v,v,v,
+                       v,v,v,
+                       v,v,v,
+                       v,v,v,
+                       v,v,v,
+                       v,v,v,
+                       v,v,v,
+                       v,v,v,
+                       v,v,v,
+                       v,v,v)
+       }
+}

and then, I try the TPCC on my local machine, and with no luck ... it doesn't reproduce

tiup bench tpcc --warehouses 10 --parts 10 prepare -T 16 -D bench
tiup bench tpcc --warehouses 10 --parts 10 run -T 16 -D bench

This change is simple enough, so maybe we can merge it first and see whether it reproduce in the future.

Side effects

  • Performance regression: Consumes more CPU
  • Performance regression: Consumes more Memory
  • Breaking backward compatibility

It should not impact the write performance in most cases, because the insert/update/delete is unparalleled
and be the bottleneck, the change of projection does't change this fact.

Documentation

  • Affects user behaviors
  • Contains syntax changes
  • Contains variable changes
  • Contains experimental features
  • Changes MySQL compatibility

Release note

None

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
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/run-all-tests

@ti-chi-bot ti-chi-bot added do-not-merge/release-note-label-needed Indicates that a PR should not merge because it's missing one of the release note labels. release-note-none Denotes a PR that doesn't merit a release note. and removed do-not-merge/release-note-label-needed Indicates that a PR should not merge because it's missing one of the release note labels. labels Dec 3, 2021
@ti-srebot ti-srebot added size/S Denotes a PR that changes 10-29 lines, ignoring generated files. type/5.2-cherry-pick type/bugfix This PR fixes a bug. labels Dec 3, 2021
@ti-srebot ti-srebot added this to the v5.2.2 milestone Dec 3, 2021
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@tiancaiamao you're already a collaborator in bot's repo.

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/run-check_dev

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This pull request is closed because it's related version has closed automatic cherry-picking.
If it's still needed, you can reopen it or just regenerate it using bot,
see:

You can find more details at:

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